Ultrasonic process and apparatus



Jan. .3, 1951 R. P. GUTTERMAN 2,967,119 ULTRASONIC PROCESS AND APPARATUSFiled Sept. 8, 1958 3 Sheets-Sheet J.

INVENTOR Ross/r7- Gurus/mm $14M, flu mw ATTORNEYS Jan. 3, 1961 R. P.GUTTERMAN ULTRASONIC PROCESS AND APPARATUS 3 Sheets-Sheet 2 Filed Sept.8, 1958 Jan. 3, 1961 R. P.'GUTTERMAN ULTRASONIC PROCESS AND APPARATUS 3Sheets-Sheet 5 Filed Sept. 8, 1958 INVENTOR K05537- GUTTERMAA/ MW,flag/W ATTORNEY 5 United States ULTRASONIC PROCESS AND APPARATUS RobertP. Gutterman, Bethesda, Md., assignor, by mesne assignments, to LipsnerSmith Corporation, Chicago, Ill., a corporation of Virginia Filed Sept.8, 1958, Ser. No. 759,591 2's Claims. c1. 134 -1) This invention isgenerally related to the art of cleaning photographic film which is, ineffect, film carrying intelligence in the form of a series ofphotographs, and is specifically directed to a novel process andapparatus for cleaning strips of photographic film using ultrasonicenergy. It is especially adapted for the continuous cleaning of motionpicture film strips but can also be used for cleaning, continuously orotherwise, of other types of photographic film such as strips of filmfrom still cameras, particularly when several such strips are attachedend to end to each other. Similar applications of this invention will beapparent from the following description.

The cleaning of motion picture film has presented a long-standingproblemof great importance to the motion picture film industry. In filming amotion picture, a single original film is obtained and this originalfilm represents the complete product of the investment of great sums ofmoney. Its careful preservation is accordingly exceedingly important.One of the first steps taken after preparation of the original film isto prepare several direct copies, which direct copies are then used toprepare the large number of exhibition prints for actual projection use.

Throughout the copying procedure, it is very important to have the filmclean at all times in order to obtain good copy prints. Any defects suchas specks of dust or dirt, any grease marks or any scratches on the filmnegative will be magnified and enhanced (a necessary result of thenature of light propagation). A negative tr neg'at ve copy which isspotted and blurred will tend to be produced and will not be entirelysatisfactory for viewing purposes. It is understandable then that everyeffort is extended by the film processors to maintain a clean originalfilm and clean direct copies thereof.

This is not an easy task, however, for even in a reel, film will tend topick up dust particles and during projection thereof dust will bereadily picked up from the atmosphere. This collection of dirt isenhanced by the tendency of film to pick up electrical charges duringunwinding and rewinding of the film on reels, the film strip acquiringsome of the characteristics of a dust precipitator. When the film isrewound, the dirt particles are, of course, embedded between adjacentportions of the inherently soft surfaces of the film backing andemulsion coatings. The winding tensions will tend to cause a certainamount of frictional slipping between adjacent film surfaces and dirtparticles therebetween will scratch the film. These scratches result inlight scattering just as grease spots will cause light diffusion andconsequently the projected image will be blurred and lack the desireddefinition of the image.

The cleaning of dirt and grease from a film surface is not, however, aneasy matter for the same reason that the dirt and grease is such aproblem. That is, any normal scrubbing operation will itself scratch thefilm, and while the use of a liquid medium is necessary to relieve thescrubbing, at the same time it will leave spots" if not carefullyhandled. The range of cleaning solvents which Patented Jan. 3, 1961 ICCmay be employed is of course limited by the solubility characteristicsof the film itself, but even with those that may be employed the wet ormoistened film tends to become softened, as is well known. Consequently,even though mechanical removal of the dirt, as by dabbing with clothpads, is easiest when the film is moistened, the danger of scratches isincreased. Only by careful treatment with moistened pads can theobjectionable spots, left by the evaporation of the solvent, be removed.

While increased temperatures may aid in evaporating cleaning solventfrom the film surface, increased temperature very directly increasessoftening of the film, and if too elevated may cause an actual physicalwarping of the image. This limitation materially reduces the facilitywith which a solvent will remove grease deposits.

Consequently, there is a real need for an improved film-cleaning methodwhich is safe, economical, rapid, and efi'icient, and which can beemployed in a commercially feasible apparatus of reasonable size andease of operation.

The present invention provides a novel method and apparatus whichaccomplish these objectives.

It is therefore an object of this invention to provide an ultrasonicmethod for cleaning photographic film.

It is also an object of this invention to provide a novel apparatus forthe ultrasonic cleaning of photographic film.

Additionally, it is an object of this invention to provide a novelnon-evaporative drying process which may be employed with. theultrasonic cleaning process for photographic film.

Still another object of this invention is to provide a novel apparatusfor the ultrasonic cleaning and nonevaporative drying of photographicfilm.

Another object of this invention is to provide a novel process andapparatus for ultrasonic cleaning and nonevaporative drying ofphotographic film wherein said portion of the film surface is subjectedto maximum ultrasonic energy.

Still another object of this invention is to provide a process andapparatus for ultrasonic cleaning of photo graphic film which willeffectively utilize the maximum generated ultrasonic energy at thephotographic film surface.

Further objects of the invention wil lappear from the followingdescription thereof.

Referring to the accompanying drawings:

Figure 1 is a schematic representation of one form of apparatus whichmay be used in this invention;

Figure 2 is a schematic representation of another form of apparatuswhich may be used in this invention;

Figure 3 is a schematic representation of still another form ofapparatus which may be used in this invention;

Figure 4 is a cross-sectional view of the novel drier which forms a partof the invention, the cross-section of the drier being the samethroughout its transverse dimension;

Figure 5 shows the approximate relationship between the appliedfrequency and sound energy density required to initiate strongcavitation in the solvents employed in this invention, as enumeratedhereinafter;

Figures 6 and 7 are schematic diagrams of the manner in which the filmpasses through the ultrasonically-activated cleaning solvent in thisinvention, standing ultrasonic waves in the solvent being illustrated aswill be hereinafter described;

An alternative method of orienting the film is illustrated in the topview of the cleaning tank shown in Figure 8;

Figures 9 and 10 illustrate, in elevation and top view respectively, apreferred support and sealing disk arrangement for the squeegee plate;and

Figures ll and 12 show, in elevation and top view respectively, apreferred form of and mounting with sealing recess for the spraysqueegees.

In order to clarify the major factors involved in ultrasonic cleaning,it may be helpful to review briefly the physical mechanisms involved.

Most liquids contain finely dispersed gases. These may be held in truesolution, entrained in molecular foun in the quasi-crystalline structureof the fluid, or adsorbed as microscopic bubbles on suspended particlesof dust. Wherever such impurities occur, the structure of the liquid isweakened and a nucleus for its rupture is present. If the temperature israised at constant pressure, approach to the boiling point is firstsignified by local rupture at such nuclei and attendant release ofexpanding gas bubbles which coalesce and rise quietly toward thesurface. As the temperature is increased, bubbles if true vapor begin toform at the same or similar nuclei. If these bubbles migrate into coolerregions of the liquid, they condense and collapse rapidly, producing anaudible hissing sound. Similar effects are noted if the pressure over aliquid is reduced while the temperature is held constant above thecritical point.

When intense sound waves are produced in a liquid, closely analogousphenomena occur. When the sound pressLre amplitude exceeds the staticpressure, the effective local pressure becomes negative during thedilational p 'iod of each oscillation. While the theoretical tensilestrength of most liquids is extremely high, in the order of 1000atmospheres, the presence of small bubbles and other rupture nuclei mayreduce this value locally to as low as 1 atmosphere. Thus, a negativepressure of this order, occurring once in each cycle of an intense soundWave, can excite effects similar to the onset of low-temperature,low-pressure boiling. Such cold-boiling" effects are referred tocollectively as cavitation."

As the sound pressure amplitude in a liquid is increased, three forms ofcavitation become apparent. When the pressure amplitude just exceeds thestatic pressure, the larger gas-bubble nuclei expand, coalesce and risequietly to the surface. This phenomenon, called quiet degassing,contributes in a minor way to cleaning of immersed objects by liftingaway loosely attached particles having relatively large quantities ofgas adsorbed on their surfaces. Continued irradiation eventually clearsthe liquid of these larger bubbles.

As the pressure amplitude is increased further, the average size ofreleased bubbles decreases and their content of molecular vapor of thesurrounding liquid increases. They occur in vast quantities, appearingto the eye as foggy streamers. This is called vaporous cavitation. Ifthe sound pressure is stopped, these bubble streamers disappear, astheir gas content dissolves and the true vapor present condenses.

When the sound pressure becomes very great, the average bubble size isreduced further, the content of the bubbles becomes largely pure vaporand a wide-band, hissing noise becomes audible. This is due to veryrapid, complete collapse of the smaller bubbles during positive pressureperiods of the applied sound waves.

A bubble of vapor suspended in a liquid constitutes an acousticresonator that will vary in diameter roughly in phase with alow-frequency, oscillating pressure field. As the applied soundfrequency is increased towards its natural resonant frequency, theamplitude of oscillation and the energy stored in the bubble becomequite large. The bubble grows during the negative pressure period andshrinks rapidly during the positive pressure period. As it shrinks, thepressure in the bubble rises very quickly, forcing some of the containedvapor to condense on the bubble wall. The reduction in radius thusbecomes unstable and the bubble collapses implosively,

releasing all of its stored energy in the form of extremely intenseshock waves. The solvent impingement of these local shock waves againstdirt particles lodged on an immersed object provides the intensescrubbing action in an ultrasonic cleaning system.

The resonant frequency of a vaporous bubble increases with decreasingdiameter. The resonant diameter is about two orders of magnitude smallerthan the wavelength of sound in the fiuid at the resonant frequency.Since only bubbles that are equal to or smaller than resonant size arecapable of rupture and collapse within one pressure cycle, it is obviousthat increasing the applied frequency will, statistically, decrease thefraction of bubbles suitable for proper cleaning action. It is fortunatethat the intensity of sound required to produce adequate cavitationremains a proximately constant and within practical limits well into theultrasonic frequency range. If this were not the case, and audiofrequencies were required, the leakage radiation from a high-poweredcleaning system would far exceed the tolerance of a human operator. Theapproximate preferred region of operation is illustrated in the graph ofFigure 5.

To apply these principles to a practical cleaning system forphotographic films, it is important that the solvent employed is anefiicient cleaner for the particular soils and dirt in question, andthat it be inert with respect to the film itself. The typical soils tobe removed in the cleaning of photographic film include solublematerials such as oil, grease, smoke, and tar particles, wax pencil, andadhesive tape residue; non-filterable insoluble particles of extremelysmall size; and the larger, filterable insoluble particles such aschips, lint, granular dirt, and the like. The nature of these soils alsoleads to particular treatments and elements in the apparatus.Furthermore, the boiling point, surface tension, and acoustic propertiesof the solvent must permit proper cavitation phenomena. Obviously, firehazard and toxic levels must also be low.

Among the materials which satisfy the requirement and which may beemployed in the present invention are aqueous detergent solutions. Thesesolutions require, however, more specialized care than other solventswhich could be used; that is, a closer control of the temperature mustbe used in order to avoid damage to the film. It is also known thatcavitation of aqueous solutions can produce significant quantities ofhydrogen peroxide. The attendant possibility of bleaching or otheroxidizing effects with respect to the latter factor is a furtherdeterrent to the use of water solutions; however, with proper care theycan be employed. It is preferred, therefore, that commercial organicsolvents which are known to be reasonably safe for use on color or blackand white films be used. Of these stabilized methyl chloroform ispresently preferred as offering the best compromise between qualitycharacteristics and cost. Other solvents which may be used includetrichloroethylene, perchloroethylene, carbon tetrachloride, and theFreons, trichloromonofiuoromethane, dichlorodifiuoromethane,dichloromonofiuoromethane, monochlorotrifluoromethane,trichlorotrifiuoroethane and dichlorotetrafiuoroethane, etc. That is,the most suitable solvents comprise these chlorinated and fiuorinatedlower alkanes, or mixtures thereof.

General description of apparatus To further understand the nature of theinstant invention, reference may be made to the accompanying draw ings.In the embodiment shown in Figure l, a film supply reel 20, equippedwith an electric brake to provide proper tension, carries the dirty filmstrip 22 which is unwound therefrom over guide roller 24 and tensioningreel 26 equipped with tension arm 28. Film strip 22 then passes intotank 30 which is equipped with piezoelectric transducers or equivalentelectromechanical ultrasonic generators 32. The fiTm is carried aroundtank guide roller 34 in a helical path such that the emulsion side doesnot touch any surface and then passes upwardly out of the tank as shownat 22'. At this point, the film passes through a pair of pressure sprayrinse nozzles or squeegees 36 which deliver clean solvent to the surfaceof the film and are operative to wash off part of the dirty solventcarried up from the tank on the film surface, and also to limit theamount of solvent thereafter carried upwards on the film, as will bemore fully described hereinafter. The film strip 22' then passes overguide roller 38 through drying chamber 40, which is illustrated ingreater detail in Figure 4. On exiting from drier 40, the clean driedfilm strip 22 passes over guide roller 42, drive sprocket 44, andtensioued guide roller 46 onto take-up reel 50. Guide roller 46 isprovided with tensioning arm 48 which also operates as a stop signaldevice. Guide rollers 38 and 42 control centering of the film in thedrier. Guide roller 34 is mounted on vertical slide means, not shown, sothat it may be removed upwardly out of the tank to facilitate theinitial threading the film strip around it. The combined torque-speedcharacteristics of the supply reel brake and the take-up reel drivemotor cause the film to run in the proper direction, even withoutengaging the drive sprocket 44; however, the synchronously drivenspocket 44 imposes a constant speed on this motion. Since primary driveenergy is supplied by the take-up reel motor, forces exerted on thesprocket holes are minimized.

In Figure 2, a modified apparatus is shown where supply reel 20 is abraked reel and the film strip 22 passes over a guide roller 24 intotank 30, fitted with piezoelectric transducers 32, around tank guideroller 34, mounted on suitable elevator means not shown, for loadingposition 34', and out of the tank through pressure spray rinse nozzles36. As shown in this figure, the solvent fed to the spray rinse nozzles36 is delivered from drain 60 through filter 63 by means of pump 64through a heat exchanger 66 which may be cooled by a fan 66', or othersuitable means, and by line 68 to the nozzles 36. Film strip 22 afterpassing through nozzles 36 then passes through an air squeegee 70 whichis operated to control the surface wetness of the film at the optimumlevel for passing upwardly over guide roller 38 into the drying chamber40. This feature assists the efficient operation of the drying chamber.On leaving the drier, film strip 22' is carried over sprocket drivesprocket 44 directly to take-up reel 5i}. An ultrasonic power generatoris schematically shown as 72.

Figure 3 illustrates a further embodiment of the invention and shows amore elegant apparatus arrangement. In this figure, film strip 22 istaken off supply reel 20 over guide reel 24 into cleaning tank 30 aroundtank guide roller 34 (which may again be elevated from the cleaning tankto position 34' for ease of loading). The wet, cleaned strip 22 leavesthe tank and passes through an air squeegee 80 over guide roller 82through cleaning spray nozzles 84 which in this case direct the spray ofclean solvent in the same direction as the movement of the film. Thefilm is then passed around guide roller 86 and through second airsqueegee 88. It will be noted that spray nozzles 84, roller 86, and airsqueegee 88 are all arranged directly above a settling and reservesolvent tank 90 which is connected to cleaning tank 30 by means of tube92.. This arrangement permits economical collection of the olvent forreuse in the cleaning tank. Tube 9?- rnny site-Ll with suitablefiltrring means (not shown) and tank 94 may contain a thermostatictemperature control device (not shown) to remove the heat generated bythe ultrasonic energy. After film strip 22 passes through :zir squeegee88. it passes over guide rollers 94 and 33 into drier 40 where thesolvent is stripped off, as will be described hereinafter. On leavingthe drier, the cleaned, dried film strip 22" passes over guide roller 42and sprocket drive 44 onto take-up reel 50.

Referring again to Figures 1 and 2, the arrangement and operation of thespray rinse nozzle 36, is very important to the successful commercialoperation of the invention. As the film moves upward out of the tank,each surface will carry a layer of the dirty cleaning solvent by naturaladhesion. it is important that the bulk of this dirty solvent be removedfrom the film surface for several reasons. One is to insure properoperation of the non-evaporative dryer device 40, discussed hereinafter,and another is to limit the consumption of solvent. In essence, nozzles36 operate as a knife-edge squeegee to remove the major portion of thesolvent layer, but still leave a thin layer thereof on the film. Thisthin layer is of sufficient thickness so that evaporative drying of thefilm does not take place while the film strip 22' is moving to the dryer40, but not so thick that it cannot be completely stripped off the filmas a liquid sheet in the dryer, see infra. In addition, when cleaningwith the nozzles 36 in operation only about 0.1 gallon of solvent per1000 feet of film (35 mm.) are lost by atmospheric evaporation, but ifoperated without the nozzles, about ten times that amount, 10 gallonsper 1000 feet of film (35 mm), would be lost. It will thus be seen, thatnozzles 36 are of great significance in the economic feasibility of theinvention.

Referring now to Figure 4, there is generally illustrated incross-section one form of the drier 40. It will be seen that drier 46comprises a drying chamber defined by side walls 102 and end wallsgenerally perpendicular thereof, not shown. Conveniently, one end wallmay be hinged to facilitate threading of the film through chamber 100.The cross-section of the drier is the same at all lateral points alongwalls 102. The film strip 22' enters chamber 100 through entry slot 106.Immediately adjacent exit slot 108 are air jet nozzles, connected to amulti-stage centrifugal air compressor, which are arranged generally asshown so as to impinge a high velocity, high volume, warm air jet ontoeither side of the film strip in a direction angularly opposed to thedirection of movement of the film, as indicated generally by lines a.When this air jet encounters the wet film at an appropriate angle, itstrips or tears the solvent layer off the film surface as a fine liquidspray with essentially complete avoidance of any evaporative removal ofsolvent from the film surface. The air jet containing the thus producedsolvent spray generally follows air stream paths b into the chamber. Inorder to prevent deposition of this spray onto the film surface,baffiing vanes 110 and 112 are arranged tandem-wise about the wet movingfilm strip at spaced points prior to its contact with the air jets. Theair stream, carrying the solvent droplets, is then deflected along theair flow path lines [7, c and d, induced by bafiie vanes 112. The airand its solvent content, now vaporized in the output airstream, is thendischarged from the drying chamber through exhaust ports 114. The rapidremoval of the air from the drying chamber is assisted by connectingexhaust pumping means (not shown) to ex haust ports 114 to impose apartial vacuum at that end of the drying chamber. Further reference tothe design characteristics of this drying chamber will be madehereinafter.

The various elements of the apparatus and steps of the process will nowbe discussed in somewhat greater detail.

Design and operation of the cleaning rank Since this invention utilizesultrasonic energy by means of the cavitation phenomena, it is importantthat cavitation occur at the surface of the film and that the energy beused to the maximum possible extent. These considerations have now beensatisfied by so constructing the tank that it may be tuned to theultrasonic frequency contemplated and by passing the film through theenergized solvent in a particular path.

As respects the tank design, it may be stated as a general propositionthat the propagation of ultrasonic energy follows the usual behavior ofsound waves. There will be, consequently, energy maxima and minima,respectively at the loops or crests, and the nodes, in the liquid bodythrough which the wave is passing or in which the standing wave ismaintained. Of more direct importance to the present cleaning processand the cavitation effect, is the correlative phenomenon of varyingpressures in the liquid or really the alternating pressure amplitudestherein. The maximum alternating pressure amplitude occurs at the nodesand the minimum at the loops of the wave. Cavitation occurs to thegreatest extent at the loci of the maximum alternating pressureamplitude, at least within the range of sound energies of practicalimportance. Hence, at the loops of the sonic wave cavitation will bemost violent and of maximum value in the cleaning operation. Keeping inmind that it is necessary that both sides of the film be cleaned andthat it is, therefore, desirable to use two opposed transducers oneither side of the film strip, one feature of the present invention isto tune the sound frequency generated by the transducers so thatsubstantially standing waves are obtained in the liquid. Not only doesthis feature avoid loss of power by wave interference destroying theloop structure, but it also establishes fairly fixed discrete regions ofmaximum alternating pressure amplitude where the ultimate cleaning isachieved.

Referring to Figures 6 and 7, which illustrate one possible cleaningtank 30 fitted with opposed transducers or equivalent sonic generators32, the loops and nodes of sound energy in the standing waves areindicated as x and y, respectively. It will be seen that the wavesextend vertically and horizontally through the solvent in verticalplanes. Overlap of the film strip, entering as 22 and exiting as 22, canbe substantially avoided by the use of the helical path previouslyreferred to.

This process of passing the film in a helical path through the tank isarranged so that the plane of the film forms an angle, both horizontallyand vertically with the plane of the standing waves. In addition, thedownwardly passing film strip 22 does not overlap the upwardly passingstrip 22 in the direction of wave propagation. Thus, any shielding of aportion of the film by another section thereof is avoided and the fullutilization of the wave energy is achieved.

Alternatively, however, this result can also be achieved by carefullyorienting the falling and rising portions 22 and 22' of the film stripin spaced parallel paths. as can be seen from the vertical view of thetank 30 in Figure 8. In this tank design, the film strips 22 and 22,shown in cross-section travel in substantially vertical paths. Here thevertical plane a of tank guide roller 34 is angularly disposed, relativeto the propagation vector b of the ultrasonic wave, and is of sufficientdiameter, that shadowing by one parallel strip of the film of the otherstrip is avoided (a may be 30). The angle a is formed by theintersecting plane a and vector b, as clearly shown in Figure 8 of thedrawing. At the same time, relative to the standing wave formationgenerated by transducers 32, each incremental portion of the film stripwill encounter a loop in either its downward or its upward journeythrough the tank.

Further, in Figure 8 there is shown a portion of the mounting cabinet150 with tank 30, fixed by flange 152 to the shelf 154 of the cabinet byappropriate means, arranged with vertical mount 156 disposed therein.Support 156 extends from above the tank substantially to the bottomthereof and serves to carry the elevator mechanism, including pulley 158and pulley shaft 160 for raising and lowering roller 34, other detailsof the elevator mechanism not being shown but generally comprising achain or belt drive on the pulley and mounting shaft of roller 34 (whichis, however, free running), and vertical track means on support 156 forthis latter shaft and a suitable driving mechanism turning shaft 160 asdesired. In addition, it is preferred to provide for simultaneouselevation and lowering of the spray squeegees to a level in the tanksubstantially below the upper opening and the solvent level. This cutsdown on solvent losses by evaporation, but still permits ready access tothe squeegees for adjustment and for cleaning.

Plate member 162 on support member 156 is shown in greater detail at thesqueegee operating level in Figures 9 and 10. Plate member 164 in Figure8 carries the squeegees and is shown in greater detail in Figures ll and12. Figures 9 through 12 are discussed hereinafter.

The structure of tank guide roller 34 shown in Figure 8 is alsopreferred. Flanges 166 and 166 are spaced to carry a wide film, forinstance 35 mm. film, and flanges 168 and 168 to carry a narrower film,for instance 16 mm. This arrangement is also carried over to the otherguide rollers 24, 26, 38, 42, and 46, and sprocket drive 44 is similarlyadapted, so that film strips of different width can be cleaned withoutchanging rollers or sprocket drives.

Thus, according to this invention, the angle of the film transverse tothe wave vector and/or the angle of the film strip relative to avertical plane are carefully selected with reference to the distancetravelled in the tank (both in vertical and horizontal components) andthe sound frequencies, i.e. wave length, so that each and every segmenton each side of the film will be guided at least once through a waveloop or node of pressure maxima. Thus, every element of the film surfacewill be exposed to a region of maximum cavitation so that the maximumcleaning over the entire film surf-ace is achieved.

Design and operation of drier The above-described process of ultrasoniccleaning of the film will not produce a final product which iscompletely satisfactory unless the film strip 22 removed from the tankis properly treated so that the solvent thereon is removed withoutredeposition of dirt. It will be appreciated that of the soil types tobe removed from the film the non-filterable small dirt particles and thesoluble greases and adhesive tape glues will remain in the solvent inthe cleaning tank. As the film is removed from the tank, a certainamount of this solvent will adhere to the surface of the film and, if itis merely evaporated, these soils would, of course, be redeposited onthe film surface. Thus, the purpose of the cleaning step would bedefeated to this extent.

At the same time, of course, the solvent must be removed from the filmand the latter dried so that it may be safely rewound without damage tothe emulsion. In order to accomplish this objective, the presentinvention utilizes in combination with the ultrasonic cleaning tank aparticular type of drier. This drier has been generally described abovein the discussion of Figure 5. In the design of the drier, certainstructural features are particularly important. These include the angleof incidence of the air jets on the film (lines a) and the angles formedby the baffie vanes with the plane of the moving film. In addition, thevelocity, volume flow, and temperature of the air jet are alsoimportant.

In satisfactory operation, the air jet should impinge on the film at anacute angle of from about to 15, preferably from 30 to 50, when an airvelocity of from 1,000 to 10,000 ft./min. and a film speed of from about10 ft./min. up to at least 360 ft./min. are

' used, the latter being greater than any conventional rate of filmcleaning. In so operating, the volume of air passing through each jetwill be from about 10 to about ft. /min./in. of film width. Whenoperating within these combined process limitations, the air jetoperates substantially completely to literally strip or tear the solventlayer directly off of the surface of the film on which it is carried. Itis then removed as a spray into the air stream and the film leaving thejet is quite dry, but completely clean since no evaporation of the dirtysolvent has taken place on its surface. In order to prevent redepositionof the droplets of dirty solvent, which are now in the air stream, atleast one bafiling vane 110 is provided, and preferably two or more, asshown in crosssection in Figure 4. These vanes have three functions: (1)to prevent evaporation of solvent prior to entering the zone of the highvelocity air jet, (2) to shield the lower portions of the film whichhave not yet contacted the air jets from the dirty solvent-spraycontaining air stream, and (3) also to direct the air stream along pathlines b out through the exhaust ports 114. In order to be effective, theangle which the sloping vane surfaces 110' and 112 forms with the planeof the film must be Within 15 to 75, preferably from about 35 to 55 with45 giving the best results, for the above stated ranges of operationwith respect to film speed and air jet velocity and flow volumecharacteristics. The aperture between the edges of surfaces 110 and 112and the film must be adequate to prevent contact so that scratching isavoided; however, the drier of this invention generally protects thisfeature by the opposed substantially equal air pressures exerted on thefilm. The width of the vane aperture may be about .02 in. to 0.5 in.,preferably .03 to 0.1 in., depending on the film speed, air streamvelocity and the particular solvent used. This distance permits acertain amount of air flow to pass along path lines c and d. Since,however, this air is saturated with solvent vapor and is travelling at ahigh velocity, its effect is again primarily to strip off the solvent asa liquid. In any event, the saturation of the air stream preventsevaporation of the film in these regions internally of the vanestructure so that the redeposition phenomenon is still avoided. Toassist maintaining the high velocity air stream throughout the drier,and to aid the removal of the solvent-containing air, the exhaust portsare preferably connected to partial vacuuminducing pumping means, butthis feature is not necessary. Because warm air is used, the initiallyremoved solvent spray droplets will evaporate into the air stream as itpasses toward and out through exhaust ports, under the influence of boththe temperature and the reduced pressure. Conventional condensers can beused in the air stream to recover this solvent if desired, but as willbe hereinafter described, the quantity is sufiiciently low so that suchloss of solvent, if the condenser is not used, is not serious. Suitableoverall height of the drier may be from about 2 to 8 inches from thenozzles 108 to entry slot 104 depending on film width and speed. Thelength of the drying chamber will be great enough to accommodate themaximum film width to be processed (i.e. up to 90 mm. or more) asdesired, and the width of the drying chamber may be from about 1 toabout inches or more. Generally, the baffling vanes will extendtransversely across the drier chamber and be closed at their ends by thewalls thereof. So long as the required features of adequate shielding ofthe film and proper angles to induce the desired air how are assured,various specific shapes for the vanes may be used.

The film strip 22" which exits from the drier over guide roller 94 isthoroughly dry and characteristically exhibits a polished surface. Dirtysolvent spots are noticeably absent and the film is remarkably clean,even when an initially extremely dirty film is employed as will bementioned hereinafter. A further feature of the drier operation is thefact that, as the film leaves the drier, there is an absence ofelectrostatic charge. Normally, the photographic film tends to pick upelectrostatic charges as it is wound and passed over rollers such as areused in establishing its path through the cleaning tank. However, suchcharges seem to be completely removed by a grounding phenomenon betweenthe spray and the walls of the drying chamber. That is, as the spray isstripped off the film surface, the droplets apparently carry off anyelectrostatic charge which has been built up on the film. This is anexceedingly beneficial characteristic of the process and of the drier,when operated and constructed as described above, since it preventsstatic scratches from developing on the take-up reel. Furthermore,static-free film is less likely to accumulate dirt and dust from itssurroundings. It will also be appreciated that any additional dechargingapparatus is unnecessary in this invention.

While the drier is an important component of the complete ultrasoniccleaning apparatus, and the drying step is an important feature of theultrasonic cleaning process of this invention, it will be appreciatedthat the instant drier does have other applications. For instance, itcan advantageously be used in film processing, i.e. developing andfixing operations, to effectively remove the chemical solutions when thefilm is passing from one stage to another, as well as the final dryingthereof after development, fixing, and washing have been completed. Inthis connection, it might be noted that the ultrasonic cleaning tankcould also be used during development, fixing, and washing stages sincethe cavitation phenomenon on the surface of the film would lead to verydesirable stirring phenomenon and prevent local concentration buildupsof the exhausted solution which is formed during the chemical reactionstaking place. At the same time, in spite of the violence of thecavitation phenomenon, which is sufiicient to induce pitting of metalsurface, it has been found that the photographic film emulsion andbacking are not damaged in any way.

Design and operation of spray rinse nozzles 0r squeegees In order forthe drier to operate properly so that both of the above desired resultsare achieved, the film must be suitably conditioned after its removalfrom the tank. As has been mentioned, air squeegees may be used as shownin Figures 2 and 3 to remove a major portion of the solvent. These areoperated, however, so that the film does retain a full layer of theliquid solvent on its surface prior to going into the drier. Otherwise,the use of air squeegees would lead to evaporation of the solvent on thefilm and the purpose of the drier would be defeated. Of course, theaction of the air squeegee will lead to solvent losses and,consequently, a further feature of the invention includes combining thefunction of the air squeegee with the spray rinse. In this embodiment,the apparatus similar to that shown in Figure l and as further shown inFigure 8 may be employed but the solvent spray rinse is operated at ahigh velocity, substantially greater and opposed to the film velocity ata critical angle less than about 25 (when using the solvent specifiedabove). The effect of this high velocity solvent spray, or wet squeegee,is to prevent the major portion of the solvent carried on the filmsurface from moving upward beyond the level of the squeegee nozzles. Byavoiding the use of an air jet, solvent losses are greatly reduced aspreviously mentioned. The angle of the spray is, however, quiteimportant for, if it were, say, 30, the downward component of thevelocity of the spray would not be sufficient to prevent a backing up ofthe liquid layer which would then be carried on the film surface abovethe wet squeegee; therefore, the angle of incidence of the spray withrespect to the film is preferably maintained about 10 and 15". Whilethis method of operation is presently preferred, it will, of course, beappreciated that the invention includes the use of an air squeegee asshown in either Figures 2 and 3, for instance.

Figures 11 and 12 show a preferred squeegee assembly and structure, andwill be discussed hereinafter with cojoint reference to Figures 9 and 10which show the structure of vertical support 156 (see Figure 8) at thesqueegee operating height in cleaning tank 30. The squeegee nozzles and170' are mounted on the front wall 172 of chamber 174 which communicateswith circular opening 176 in squeegee plate member 164. This platemember 164 is provided with clamp-shaped flanges 178 adapted to looselyand slidably engage the edge 180 of vertical support plate 162, therebypermitting the squeegee assembly to freely travel up and down on supportplate 162. Communicating with chamber 174 are L-shaped conduits 182 and182, adapted to deliver solvent through openings 184 and 184' on faces186 and 186 of the squeegee nozzles 170 and 170'.

Solvent for operating the squeegees is delivered by pipe 188 (Figures 9and 10) to chamber 190 arranged rear wardly of support plate 162 behindresilient disk portion 192, as shown. The resilient disk 192, preferablyformed of a material such as Mylar, is provided with a small hole orport 194 adapted to permit solvent to pass outwardly therethrough.However, the delivered solvent pressure in pipe 188 is maintainedsufficiently high so that it cannot be entirely relieved by the solventjet egressing through hole 194, and consequently the pressure build-upbehind resilient disk 192 will cause it to expand outwardly and toassume the form of dotted line 196 (Figure 10).

In operation, after the film is loaded on the equipment, and threadedover tank guide roller 34 (Figures l-3 and 8), the elevator mechanismlowers it from position 34'. The squeegee assembly will initially be outof the tank above roller 34 and will simultaneously slide down onvertical support plate 162 until stopped by lugs 198 and 198, orequivalent means, with disk member 192. At this point, the pumpdelivering solvent through pipe 188 is turned on (automatically by aswitch coupled with the elevator mechanism) and disk 192 expends to line196, and the periphery 196a will firmly seat against the peripheralsurfaces 176a of plate 164 adjacent opening 176. Conveniently, disk 192may be provided with concentric corrugations to assist the sealingengagement, with port 194 then located in a flat central area of thedisk. In this manner, an excellent seal is provided so that there willbe no pressure losses between hole 194 and conduit openings 184 and ahigh velocity solvent jet can be obtained from the latter on squeegeeface 186. At the same time, it will be seen that the squeegee assemblyis otherwise free to slide upwardly on support plate 162 when thesolvent pump is turned off, when the film has been completely removedfrom reel 20 (Figures l-3). Actually, clamp-shaped member 178 can bevery loosely fitted to the edges 180 and 180' of support plate 162, sothat there is considerable play between plate 162 and plate 164, and atight seal at walls 176a will still be obtained.

It will be clear that the film strip 22' travels upwardly throughsqueegee nozzles 170 and 170' and the solvent jet is deflected ofdeflector faces 200 and 200' to spray downwardly and impinge on the filmat the critical angle, velocity and volume. Film strip 22' will bemaintained spaced from walls 202 and 202' by the positioning of guiderollers 34 and 38, and particularly by the equally opposed forcesexerted by the respective solvent sprays from nozzles 170 and 170 sothat scratch damage to the film is avoided.

Tension roller switching arrangement In order to insure smooth operationof the film cleaning process, a further feature of the invention is toconple the actuating switching means for takeup reel 50 and sprocketdrive 44 with tensioned guide roller 46. and also to incorporate withthe latter a general cut-out switch for the entire apparatus. Thisembodiment will be described with reference to Figure l, but it will beunderstood that the same automatic switching system can also be employedwith the arrangements shown in Figures 2 and 3,

Referring then to Figure l, tensioned roller 46 and upwardly tensionedarm 48 opposing the downward force of film strip 22", are shown in thenormal running position. During this phase, the tension and torque driveon take-up reel 50 is adjusted so as to provide the optimum windingtension. However, it will be seen that at the start of the operation,which occurs when tank roller 34 reaches its position shown at thebottom of tank 30, and at which time the motor driving sprocket 44 andreel 50 are first turned on, the reel 50 will take a significantlygreater time, due to inertia, to reach the film take-up speed equivalentto the linear film speed provided by sprocket drive 44. Thus, a flyingloop of film will develop between sprocket 44 and reel 50, and unlessthis condition is corrected the film will probably lose its threadedposition on sprocket 44 and rollers 42 and 46, thus preventing furtheroperation.

To avoid the above events, a cut-off switch for sprocket 44 isassociated with tensioned arm 48. When sprocket 44 begins to feed filmover roller 46 to reel 50 faster than reel 50 can wind it up, thedownward tension on roller 46 is released so that it and arm 48 swing upto positions 46a and 48a. When this happens, the switch cuts off thepower to motor driving sprocket 44, but the drive on reel 50 continues.Thus, the feed is stopped until the inertia of reel 50 is overcome atwhich time the reestablished tension on film strip 22" will return thetensioned guide roller and arm to positions 46 and 48 as shown,reactivating the drive on sprocket 44. While reel 50 assumes therequired speed within a couple of seconds, the importance of thisswitching arrangement to smooth operation of the entire apparatus willbe appreciated.

In addition, a master cut-otf switch for the entire apparatus isprovided when arm 48 is in position 48!). This takes place at the end ofa given cleaning operation when the film strip has been removed fromsupply reel 20, all tension by strip 22 then being released. This mastercut-off switch then automatically shuts off the entire apparatus andobviates the necessity of an end-of-thecycle observation by theoperator. In addition, the machine will be shut off in the event of afilm breakage.

To maintain the proper tensioned operating position of roller 46 and arm48, use is made of tensioned roller 26 and arm 28 which controls theelectric braking torque on supply reel 20. Various other automaticswitching features are also preferred, such as the previously mentionedactuation of the solvent pump by the elevator mechanism after thesquegee assembly (Figures 9-12) is in sealing position; actuation of thetransducers and dryer blowers also by the elevator mechanism, while tankroller 34 is still on its downward journey to the operating position, sothat full energy will be developed when the film is ready to be run; andautomatic actuation of the motors driving sprocket 44 and reel 50 againby the phase of the elevator mechanism, when this latter position ofroller 34 is reached.

Illustrations of the practice and efiectiveness 0f the invention Theeffectiveness of this invention has been very effectively demonstratedby deliberately preparing extraordinarily dirty film. For instance,spliced sections of black and white and color films were copiouslyspotted with oil and rubber in with fingers to produce heavy fingerprints. The contents of an ash tray were distributed heavily over thesurface and other portions were marked on with editors grease pencil.The remaining areas were spotted with adhesive material of Scotchmarking tape in amounts sufficient to cause trouble in unreeling thefilm. This material was applied by soaking the tape in solvent andrubbing the softened adhesive onto the film while still wet. After thistreatment, the film was rolled tightly and cinched to assure deepembedment of the more abrasive soils. After treating such dirty filmaccording to this invention, it was found that all of the applied soilswere removed except for a few small spots of the tape adhesive andtraces of a fluorescent dye which had migrated into the emulsion fromthe red grease-pencil. It was found that these dye traces do not printin normal process and occur only when certain brands of greasepencil areemployed. As might be expected, the test films were severely scratchedduring the application of the various soils. Examination of thescratches under a glass showed that the ultrasonic cleaning had not onlyremoved the surface dirt but had also cleaned all soils from within thescratches themselves. The sprocket hole edges were similarly cleaned.Both 16- and 35-millimeter negatives were used in such tests at speedsof about 60 feet per minute.

The removal of the Scotch tape adhesive material was probably incompletein these tests because, while ultrasonic action effectively detachesthese masses from the film, they tend to swell in the solvent, formingrelatively large sticky spheroids. These resist complete solution longenough to experience strong untrasonic radiation pressure forces whichhold them against the film surface. The use of a pressure spray rinse,as described above with reference to Figure 1, will strip away suchloosened soils, returning them to the tank, where they ultimatelydissolve. This is an additional function of the high velocity wet spray.

In a further test of the invention, film strips were deeply scratchedthrough the emulsion with a needle and oily cigarette ashes were rubbedin with finger pressure. After dipping a section of this film intoultrasonically activated solvent for two seconds, this dirt wascompletely removed. In other cases, prepared dirty film, including filmmarked with difficultly removed soils such as from editors greasepencil,have been placed in the cleaning tank with the ultrasonic power turnedoff. Practically no cleaning effect takes place. When the power isturned on, however, the dirt is seen to erupt suddenly away from thefilm. This test illustrated that the ultrasonic action was primarilyresponsible for the cleaning, the solvent characteristics of the liquidemployed being important mainly for the solution of the soils afterremoval from the film surface.

In other tests, film strips were completely cleaned after being pulledrapidly between velvet pads to develop a considerable static charge andthen laid on a hall corridor carpet to pick up wool, lint, and sandydirt. This test illustrated that the ultrasonic cleaning method waseffective against dirt held by the electro-static charge.

In another test, the film test strip was liberally spotted on theemulsion side with a non-abrasive emulsion of corn starch and solvent. Asmall amount of heavy mineral oil was then added to the mixture to bindthe starch on the film surface. When the solvent evaporates, this finelydivided soil is extremely difficult to remove. The strip was thencleaned according to this invention and complete removal of the soil wasobserved.

The above tests were carried out using tanks and apparatus having thedesign characteristics illustrated above and using film speeds of from30 to 125 feet per minute.

It will be appreciated that within the range of essentialcharacteristics described above, various modifications of this inventionmay be made without departing from the essential principles thereof.Accordingly, this invention is limited only by the spirit and scope ofthe following claims.

I claim:

1. A process for the ultrasonic cleaning of photographic film whichcomprises ultrasonically activating a film-cleaning solvent, passingsaid film through said solvent, removing clean film from the solvent andthereafter completely stripping the solvent as a liquid from the surfaceof said film completely covered with a continuous solvent layer, therebynon-evaporatively drying said film surface.

2. The process of claim 1, wherein said solvent is activated byultrasonic energy continuously generated over a narrow frequency band.

3. The process of claim 1, wherein said solvent is activated byultrasonic energy generated pulse-wise.

4. The process of claim 1, wherein said solvent is activated byultrasonic energy generated so as to maintain standing waves in saidsolvent.

5. A process for the cleaning of dirty photographic film which comprisesultrasonically activating a filmcleaning solvent, passing said filmthrough said solvent and offsetting the movement of said film withrespect to the propagation vector of said activation, so that eachportion of the film passes through a region of maximum activation insaid solvent, removing the cleaned film from said solvent, andthereafter removing the solvent from the surface of said film.

6. Process for cleaning dirty photographic film which comprisesdelivering said dirty film to an ultrasonicallyactivated film-cleaningsolvent, passing said dirty film through said solvent along a helicalpath so that each portion of the film passes through at least one of theultrasonically-produced pressure alternating amplitude maxima.

7. A continuous process for cleaning photographic film by means ofultrasonic energy which comprises continu ously passing a strip of dirtyphotographic film into an ultrasonically activated cleaning solvent,maintaining the entering dirty film and exiting clean film in spacedrelationship so that substantial overlap of respective portrons of saidfilm in a plane of energy propagation is avoided, and thereafterangularly impinging air jets on opposite sides of said cleaned film soas to remove the solvent therefrom as a liquid, thereby drying saidcleaned film While shielding the wet portions of said film prior tocontact with said air jets from the ambient atmosphere and from theresulting solvent-containing air stream.

8. Process for the ultrasonic cleaning of photographic film whichcomprises ultrasonically activating a filmcleaning solvent, passingdirty photographic film through said solvent along a path successivelyencountering alternating pressure amplitude maxima, removing the cleanfilm from said solvent, angularly impinging a solvent spray onto thesurface of said clean film to remove a portion of the solvent containedthereon but leaving an entire layer of said solvent on the film surface,thereafter angularly impinging a high velocity air jet onto the surfaceof said film thereby stripping substantially said entire layer from saidsurface as a liquid, while shielding the Wet portion of said film priorto contact with said air jet from the ambient atmosphere and from theresulting solvent-containing air stream, and obtaining thereby clean dryphotographic film.

9. Apparatus for the ultrasonic cleaning of photographic film whichcomprises a tank for a suitable cleaning solvent, means for applyingultrasonic energy to said solvent, means for delivering said film tosaid tank, means for removing said film from said tank, and means formaintaining said film offset to the propagation vector of saidultrasonic energy.

10. Apparatus for the ultrasonic cleaning of photographic film whichcomprises a supply reel, means for removing film from said supply reel,a tank for a suitable cleaning solvent, means for delivering film tosaid tank, guide means for maintaining respective portions of said filmin said tank in spaced offset relationship, means for removing said filmfrom said tank, means for applying a solvent spray to the surface of thefilm after its removal from said tank, dryer means for substantiallycompletely removing the solvent from the surface of said film as aliquid, and means for winding the clean film delivered from said dryermeans.

11. The apparatus of claim 10, which further comprises a drive wheel forwithdrawing said clean, dry film from said dryer means, driving meansfor said wheel, a take-up reel for winding said clean, dry film, anddriving means for said take-up reel, and tensioning means responsive tothe tension of said film intermediate said wheel and said takeup reel,and regulatory means coupled to said tensioning means for diminishingthe speed of said wheel when the tension of said film is less than apredetermined amount.

12. The apparatus of claim 10, wherein said solvent spray meanscomprises a pair of opposed spray nozzles communicating with a means forsupplying a pressurized solvent, said film passing between said nozzles.

13. The apparatus of claim 12, further comprising elevator means forremoving said guide means and said solvent means from said tank,resilient sealing means associated with said elevator means, and meansassociated with said solvent spray means for receiving said resilientsealing means in the operative sealing relationship.

14. Apparatus for the non-evaporating drying of photographic filmsurface coated with liquid, which comprises walls defining a dryingchamber, wetted film inlet means at one end of said chamber and dry filmoutlet means at the other end of said chamber, means disposedsubstantially adjacent said outlet means and adapted for angularlydirecting an air stream onto the surface of said film, means forshielding wet portions of the film within said chamber from the ambientatmosphere and the resulting solvent-containing air stream, downstreamfrom said air stream, and means for exhausting said air stream from saidchamber.

15. Apparatus for the non-evaporative drying of a liquid from thesurface of a moving photographic film which comprises in combinationwalls defining a drying chamber, film entry means permitting continuousintroduction of a wet film strip into said chamber and film exit meansfor permitting the continuous withdrawal of dry film from said chamber,air inlet means for impinging an air blast onto the surfaces of saidfilm inlet adjacent said exit means, the direction of said air blastbeing angularly opposed to the direction of movement of said film,baffie means within said chamber for deflecting the resulting air streamaway from the surface of said film to a region downstream of said airblast, and exhaust means for removing said air stream from said chamber.

16. In the apparatus of claim 15, wherein said discharge means includepumping means for withdrawing said air stream.

17. The apparatus of claim 15, wherein a plurality of said baffle meansare employed.

18. The apparatus of claim 15, wherein said bafile means comprise wallsextending circumferentially around and spaced away from said filmincluding wall portions inclining in the direction of movement of saidfilm.

19. A process for the ultrasonic cleaning of intelligencecarryingphotographic film comprising ultrasonically activating a film-cleaningsolvent, passing said intelligencecarrying film through said solvent,thereby cleaning said film, and thereafter completely stripping thesolvent as a liquid from the surface of said intelligence-carrying filmcompletely covered with a continuous solvent layer, therebynon-evaporat'ively drying said film surface.

20. A process for the cleaning of dirty photographic film comprisingultrasonically activating a film-cleaning solvent, passing said filmthrough said solvent in offsetting relationship with respect to thepropagation vector of said activation, thereby causing each film portionto pass through a region of maximum activation in said solvent, therebycleaning said film, removing the cleaned film from said solvent, andthereafter non-evaporatively removing the solvent from said filmsurface.

21. A process for the ultrasonic cleaning of intelligencecarrying filmcomprising ultrasonically activating a filmcleaning solvent, passingsaid intelligence-carrying film through said solvent in offsettingrelationship with respect to the propagation vector of said activation,thereby causing each film portion to pass through a region of maximumactivation in said solvent, thereby cleaning said film, removing thecleaned film from said solvent, and thereafter non-evaporativelyremoving the solvent from said film surface.

22. A process for cleaning dirty photographic film which carriesintelligence comprising delivering said intelligence-carrying film to anultrasonically-activated filmcleaning solvent, passing said dirty filmthrough said solvent along a helical path, thereby causing each portionof said film to pass through at least one of the ultrasonically-producedpressure alternating maxima.

23. A process for the ultrasonic cleaning of intelligence-carrying filmcomprising ultrasonically activating a film-cleaning solvent, passingsaid intelligence-carrying film through said solvent along a helicalpath, thereby causing each portion of said film to pass through at leastone of the ultrasonically-produced pressure alternating amplitudemaxima, and thereafter non-evaporatively removing the solvent from saidfilm surface, thereby simultaneously cleaning and decharging said film.

24. A continuous process for cleaning intelligencecarrying film by meansof ultrasonic energy comprising continuously passing a strip of dirtyfilm carrying intelligence thereon into an ultrasonically activatedcleaning solvent, moving said film through said solvent along a helicalpath, and thereafter angularly impinging air jets onto the surfaces ofsaid film in a direction opposed to said movement while shielding thewet portions of said surfaces prior to contact with said air jets fromthe resulting solvent-containing air stream, thereby simultaneouslycleaning and decharging said film.

25. A process for the ultrasonic cleaning of intelligence-carryingphotographic film comprising ultrasonically activating a film-cleaningsolvent, passing said film through said solvent, removing clean filmfrom said solvent, and thereafter completely stripping the solvent as aliquid from the film surfaces completely covered with a continuoussolvent layer, thereby simultaneously cleaning non-evaporatively, dryingand decharging said film.

26. Apparatus for the ultrasonic cleaning of intelligence-carrying film,comprising, in combination, a supply reel, means for removing film fromsaid supply reel, a tank for a suitable cleaning solvent, means forapplying ultrasonic energy to said solvent, means for delivering saidfilm to said tank, means for maintaining said film in said tank offsetto the propagation vector of said ultrasonic energy, means for removingsaid film from said tank, means for applying a solvent spray to the filmsurface, means for the simultaneous decharging and nonevaporativeremoval of the solvent from the film, and means for winding the cleanfilm delivered from said decharging and non-evaporative solvent removalmeans.

27. Apparatus for the non-evaporative drying of an intelligence-carryingphotographic film surface coated with a cleaning solvent, comprising, incombination, walls defining a drying chamber, wetted film inlet means atone end of said chamber, dry film outlet means at the other end of saidchamber, means disposed substantially adjacent said outlet means forangularly directing an air stream onto the surface of said film, andmeans for shielding met portions of said film from the ambientatmosphere and from the resulting solvent-containing air stream, saidshielding means being within said chamber downstream from said airstream, said chamber having air exhaust ports.

28. Apparatus for the non-evaporative drying of a cleaning solvent fromthe surface of a moving intelligencecarrying photographic filmcomprising, in combination, walls defining a drying chamber, film entrymeans for permitting continuous introduction of a wet film strip intosaid chamber, film exit means for permitting the continuous withdrawalof dry film from said chamber, said film entry means and said film exitmeans being spaced from said film entering and exiting from,respectively, said chamber, air inlet means for impinging an air blastonto the surface of said film in a direction angularly opposed to thedirection of movement of said film, said air inlet means beingpositioned adjacent said film exit means, and baffle means fordeflecting the resulting air stream away from the surface of said filmto a region downstream of said air blast, said bafile means beingpositioned within said chamber, said chamber having air exhaust ports.

amplitude (References on following page) UNITED STATES PATENTS ScharrerMay 5, 1896 Naugle June 18, 1929 5 Inglefeld Dec. 17, 1929 Moss Mar. 26,1940 Herbert Mar. 4, 1941 Ofien Dec. 2, 1941 18 Capstafi July 14, 1942Pendleton Oct. 7, 1952 Lorig Sept. 7, 1954 Massa Feb. 15, 1955 DunglerFeb. 28, 1956 Kenmore June 5, 1956 Kearney Aug. 13, 1957 Engelhardt July14, 1959

1. A PROCESS FOR THE ULTRASONIC CLEANING OF PHOTOGRAPHIC FILM WHICHCOMPRISES ULTRASONICALLY ACTIVATING A FILM-CLEANING SOLVENT, PASSINGSAID FILM THROUGH SAID SOLVENT, REMOVING CLEAN FILM FROM THE SOLVENT ANDTHEREAFTER COMPLETELY STRIPPING THE SOLVENT AS A LIQUID FROM THE SURFACEOF SAID FILM COMPLETELY COVERED WITH A CONTINUOUS SOLVENT LAYER, THEREBYNON-EVAPORATIVELY DRYING SAID FILM SURFACE.
 9. APPARATUS FOR THEULTRASONIC CLEANING OF PHOTOGRAPHIC FILM WHICH COMPRISES A TANK FOR ASUITABLE CLEANING SOLVENT, MEANS FOR APPLYING ULTRASONIC ENERGY TO SAIDSOLVENT, MEANS FOR DELIVERING SAID FILM TO SAID TANK, MEANS FOR REMOVINGSAID FILM TO SAID TANK, MEANS FOR REMOVING SAID FILM OFFSET TO THEPROPAGATION VECTOR OF SAID ULTRASONIC ENERGY.
 14. APPARATUS FOR THENON-EVAPORATING DRYING OF PHOTOGRAPHIC FILM SURFACE COATED WITH LIQUID,WHICH COMPRISES WALLS DEFINING A DRYING CHAMBER, WETTED FILM INLET MEANSAT ONE END OF SAID CHAMBER AND DRY FILM OUTLET MEANS AT THE OTHER END OFSAID CHAMBER, MEANS DISPOSED SUBSTANTIALLY ADJACENT SAILD OUTLET MEANSAND ADAPTED FOR ANGULARLY DIRECTING AN AIR STEAM ONTO THE SURFACE OFSAID FILM, MEANS FOR SHIELDING WET PORTIONS OF THE FILM WITHIN SAIDCHAMBER FROM THE AMBIENT ATMOSPHERE AND THE RESULTING SOLVENT-CONTAININGAIR STREAM, DOWNSTREAM FROM SAID AIR STREAM, AND MEANS FOR EXHAUSTINGSAID AIR STREAM FROM SAID CHAMBER.